(1) Field of the Invention
This invention relates to a hair waving agent which has low irritativeness and the good capability of wave formation.
(2) Description of the Prior Art
The most widely used method of waving hair as desired is a permanent waving method in which a first solution for permanent waving, which contains as a principal component a reducing agent such as thioglycollic acid or cysteine, is used to open the SS linkage in the hair by reduction, thereby releasing the linkage between side chains of amino acids. This permits ready waving of the hair. Subsequently, a second solution for permanent waving comprises as its main component an oxidizing agent such as a bromate, a perborate, hydrogen peroxide or the like so that the linkage is closed by oxidation and the waved hair is fixed.
The most widely employed reducing agent used in the first permanent waving solution is thioglycollic acid. However, this acid has the disadvantages that it has inconveniently an offensive odor and gives an objectionable feel to users and is irritative. In addition, it produces great damages to hair.
A first solution using cysteine instead of the thioglycollic acid has been developed and is now in use. Although the offensive odor is reduced as compared with thioglycollic acid, cysteine is undesirably low in reducing force, so that a satisfactory degree of waving cannot be obtained. Moreover, cysteine readily suffers oxidation with air and is converted into a substance insoluble in water. This deposits on the hair or skin, thus impeding the appearance and feel or causing the skin to be chapped.